Stochastic Characteristics Of Wind Loads On A Super Long-span Roof Structure Of Multiple Corridors

The long-span roof has the advantages of aesthetically geometric diversity and spacious space;therefore,it has been widely used for many public buildings.Currently,Load code for the design of building structures(GB50009-2012)regulate that the wind tunnel tests should be conducted to investigate the wind effects on the long-span roof.In addition,the flow in the vicinity of the long-span roof is quite complex and featured by impingement,separation,and reattachment due to the sharp roof edge,roof corner,and long after-body length.Therefore,the wind pressures on the long-span roof are intrinsically non-Gaussian.Meanwhile,the post-disaster survey indicts that the peak wind pressures are the main reason that causes the local damages of long-span roofs.However,the specifications of peak factors for wind loads in the existing standards or codes are usually based on the assumption that the wind pressures are Gaussian,which would underestimate the peak wind pressures of long-span roof.And it raises a great concern of the safety and reliability of long-span roof under extreme wind events.As a result,it is of urgency and necessity to develop the peak value estimation method for the non-Gaussian wind pressures.On the other hand,during the design stage,it is indispensable to partition the wind loads in order to reduce the cumbersome work for the load combinations.Nevertheless,the load partition is always empirically performed,which would be greatly influenced by the expertise and experience of engineers involved.Hence,it is required to develop the reliable and objective method of the wind load partitions for the large-span roof.The main contents of this study include:(1)Based on the wind tunnel test of the rigid model,the mean and fluctuating wind pressure coefficients of the long-span roof of multiple corridors were analyzed and discussed.The high-order moment method and Kolmogorov's test are adopted to examine the non-Gaussian features of wind pressures on the long-span roof.The results show that the wind pressures on the roof eaves and corners are intrinsically non-Gaussian.(2)Three peak factor methods that are based on the zero-crossing rate theory,including the improved peak factor method,the Sadek-Simiu method and the objective-probability method were employed to estimate the peak factors of wind-induced pressures.All methods have their own defects.Compared to other methods,the accuracy of Sadek-Simiu method is more accurate.(3)To overcome the defect that the traditional peak factor method cannot consider the influence of bandwidth,a modified method which can take account into the bandwidth effects is proposed.The results obtained by the proposed modified method are closest to the observed peak factors as compared to the other existing methods.The average error is about 10% under different conditions.(4)The design wind loads on cladding and components of a long-span roof were investigated using both the foreign methods and the method in GB 50009—2012.The recommended peak pressure coefficients on cladding and components of long-span roof were proposed.All wind directions are divided into three wind direction zones according to the correlation coefficients and grey correlation analysis.A quick zoning method for the wind pressure coefficient has been proposed,which is based on K-means clustering.The results show that the improved method can properly develop wind pressure coefficient zoning for roofs of various geometries in a variety of conditions.